Improvement of Cs3Cu2I5 Single-Crystal Growth Process by YCl3 Additives: Cu+ Oxidation Inhibition and Precursor Colloid Stabilization

Cs3Cu2I5 single crystals are regarded as promising next-generation scintillators due to their large Stokes shift and low self-absorption characteristics. However, the cost-effective solution growth method faces critical challenges: the instability of colloidal precursors in solutions and the severe oxidation of Cu+ during crystal growth. This study innovatively introduces yttrium chloride (YCl3) as a dual-functional additive to address both issues simultaneously. The hydrolysis of YCl3 creates a controlled acidic environment, effectively suppressing the oxidation of Cu+; meanwhile, it enhances the stability of colloidal precursors by significantly increasing their surface charge and narrowing the particle size distribution. These synergistic effects enable the rapid growth (approximately 100 h) of near-centimeter-sized Cs3Cu2I5 single crystals with high crystallinity, without the need for inert gas protection. The optimized crystals exhibit exceptional performance: a photoluminescence quantum yield (PLQY) of 93.22% ± 0.47%, a scintillation decay time of 210.04 ns, and a light yield of ~738.14 pe/MeV. This YCl3-mediated growth strategy establishes an efficient approach for the solution-based synthesis of high-quality Cs3Cu2I5 single crystals, holding great significance for advancing high-sensitivity, environment-stable radiation detection applications such as medical diagnostics and nuclear safety monitoring.